The present invention relates broadly to cyclone separator tubes, and, in particular, to an improved cyclone separator tube having a side outlet for clean air, and an improved means for generating a vortex in the axial flow of contaminant laden air through the separator tube.
The prior art includes two basic types of cyclone separator tubes. In a straight-through axial flow separator tube, such as that disclosed in U.S. Pat. No. 3,517,821, contaminated air enters the separator tube and passes through a helical vane device which generates a vortex in the flow of the contaminant laden air. A clean air outlet conduit is disposed near the outlet of the separator tube and concentrically positioned with respect to the tube. A contaminant output channel is defined by the exterior surface of the clean air outlet conduit and the inner surface of the separator tube. The contaminants are thrown outward toward the inner surface of the separator tube and are discharged through the defined channel. Clean air passes axially into the clean air outlet conduit. High flow rates are achieved in the straight-through axial flow separator tube by providing a scavenge air flow. The scavenge air flow facilitates the contaminant exhaust flow by minimizing turbulence and thereby permitting higher flow rates within the separator tube.
Reverse flow cyclone separator tubes are also known in the prior art. Examples of such separator tubes are disclosed in U.S. Pat. Nos. 3,517,821; 3,498,461; 2,889,008; and 2,887,177; which are assigned to the assignee of the present application. In the reverse flow cyclone separator tube, a clean air outlet is concentrically disposed within the separator tube near the inlet end thereof. Flow deflecting vanes at the inlet of the separator tube again generate a vortex in the axial flow of contaminant laden air into the separator tube. The contaminants are discharged via straight-through axial flow. Clean air, on the other hand, reverses its flow entering the clean air outlet conduit. The pressure drops experienced in the reverse flow cyclone separator tubes necessitate a clean air outlet conduit having a length at least as long and preferrably greater than the length of the separator tube. Thus, the reverse flow devices are somewhat bulky and do not permit compact packaging within an air cleaner. Additionally, the reverse flow devices have lower throughput than straight-through axial cyclone separators. In an air cleaner housing, both prior art cyclone separator tubes, i.e. straight-through flow or reverse flow, require substantial space for manifolding of clean air from the separator tubes to a final filter element.
In the above-mentioned U.S. Pat. No. 3,517,821, a helical vane vortex generating element is disclosed. This prior art vortex generating element includes a trailing end having a surface which tapers toward the clean air outlet conduit. It was found that with this vortex generating element structure some of the lighter contaminants became entrapped at the inner periphery of the vortex and would thereby enter the clean air outlet conduit, decreasing the efficiency of the contaminant separation.
The side outlet cyclone separator tube of the present invention combines the advantages of high flow rates and efficiency of a straight-through axial cyclone separator with the non-scavenge flow characteristics of a reverse flow cyclone separator. The side outlet cyclone tube also provides for reduced packaging requirements by minimizing the space required by the prior art devices for manifolding fluids from the separator tubes to the final filter. Additionally, the present invention incorporates an improved vane structure for generating a vortex in the flow of contaminant laden air that can also be utilized to increase the efficiency of the prior art straight-through cyclone separator by directing contaminants trapped at the inner periphery of the vortex toward the side wall of the separator tube.